[Whole-body retention of 99mTc-methylene diphosphonate in skeletal diseases]

The 24 h-whole-body retention (WBR), determined by a whole-body counter, may be used to quantify exactly bone seeking properties of a radiopharmaceutical. The 24h-WBR of 99mTc-methylene-diphosphonate was determined in 200 patients and was found to be independent of kidney function if this function was normal or only slightly diminished. The 24h-WBR was slightly dependent on age since it decreased up to 20 years of age, reaching a minimum at 20-25 years, and then increased with increasing age. Normal values of 24h-WBR for individuals of more than 20 years of age were 31.8 +/- 5% of injected dose. Not more than two focal accumulations, i.e. skeletal metastases, failed to elevate the 24h-WBR significantly (p less than 0.1). However, a highly significant (p less than 0.001) difference to normals was found in patients with multiple metastases (24h-WBR: 38.2 +/- 7%), with diffuse osseous involvement as in primary hyperparathyroidism (24h-WBR: 49 +/- 11.7%, p less than 0.001) or with osteoporosis (24h-WBR: 45%). The 24h-WBR was found to be very sensitive in grading diffuse osseous involvement. This was shown in single-tumor patients by follow-up as the 24h-WBR in addition to bone scans was useful to describe progression or remission. Moreover, the 24h-WBR correlated closely with results of bone marrow biopsies in a small group of patients with malignancies of the lymphoreticular system.